But seriously, though...
Not that this will be news to anyone, but expansion is being driven by the almighty dollar. Therefore the biggest targets for the Big Ten will still be those who add the most eyes to the Big Ten Network, added bonus if they can actually give a good product on the field/court.
Biggest Targets: Texas, Notre Dame, North Carolina.
Secondary Targets: Oklahoma, UConn, UVA, Mizzou, Georgia Tech
I can't envision any scenario where Pitt or Iowa St. ever gets the invite...
I honestly don't understand why Virginia Tech never comes up in this discussion, but if the Big Ten had to expand and I could make the choice, I would offer the invite to Army and Navy. Army has an amazing history in football, and Navy has been quite good recently. They both reach a very loyal, national fanbase, and don't over-extend the reach of the Big Ten. Just add them to the East, kick Indiana to the West with Purdue, and voila!